Direct and Reverse Chemical Garden Patterns Grown upon Injection in Confined Geometries

Abstract

Spatial precipitate patterns resulting from the growth of chemical gardens in a confined quasi-two-dimensional horizontal geometry are studied experimentally upon radial injection of a solution of one reactant into the other at a fixed flow rate. We show that, at large enough concentrations, the patterns are different when injecting a solution of cobalt chloride into a solution of silicate (the direct case) than in the reverse case of silicate displacing the metal-ion solution. We discuss the possible influences of the viscosity ratio, density difference, pH, and concentrations of the reactants on the dynamics observed and characterize quantitatively the growth of some typical structures.

Filament dynamics in confined chemical gardens and in filiform corrosion

“…[14][15][16] In order to study their erratic growth, we perform image analysis. Each filament track is binarized and subsequently skeletonized as shown in Fig.…”

“…The shape of the histogram is essentially symmetric with . 16 The arrow indicates the growth direction. Scale bar represents 1 cm.…”

“…This feature is obviously a strong deviation from a simple reflection law and is reminiscent of similar dynamics observed in the chemical garden system. 16 Another important feature of filiform corrosion is the selftrapping of the travelling corrosion cells in their own or another cell's corrosion trails. This situation is shown in Fig.…”

“…Such confined chemical gardens produce an array of morphologies, among which filaments are prominent. [14][15][16] The links between chemical gardens and certain types of corrosion are well established. Corrosion tubes are hollow tubular structures that have been noted and studied in iron corrosion under a variety of conditions.…”

Wavy membranes and the growth rate of a planar chemical garden: Enhanced diffusion and bioenergetics

“…The seed particle may be replaced by injected salt solutions (24). Furthermore, one can reduce the dimensionality of the system by the injection of salt solutions from a point-like source into a thin, horizontal layer of silicate solution contained within a Hele-Shaw cell (25)(26)(27). This approach was taken further by studying the formation of precipitate membranes in a microfluidic device at the planar interface between two parallel, cocurrent reactive fluid streams (28).…”